Iron isotope fractionation during microbial reduction of iron: The importance of adsorption

G. A. Icopini, A. D. Anbar, S. S. Ruebush, Ming Tien, Susan Louise Brantley

Research output: Contribution to journalArticle

162 Citations (Scopus)

Abstract

In experiments investigating the causes of Fe isotope fractionation, the δ56/54Fe value of Fe(II) remaining in solution (Fe(II)(aq)) after reduction of Fe(III) (goethite by Shewanella putrefaciens is ∼-1.2‰ relative to the goethite, in agreement with previous research. The addition of an electron shuttle did not affect fractionation, suggesting that Fe isotope fractionation may not be related to the kinetics of the electron transfer. Furthermore, in abiotic, anaerobic FeCl2(aq) experiments in which approximately one-third of Fe(II)(aq) is lost from solution due to adsorption of Fe(II) onto goethite, the δ56/54Fe value of Fe(II)(aq) remaining in solution is shifted by -0.8‰ relative to FeCl2. This finding demonstrates that anaerobic nonbiological interaction between Fe(II) and goethite can generate significant Fe isotope fractionation. Acid extraction of sorbed Fe(II) from goethite in experiments reveals that heavy Fe preferentially sorbs to goethite. Simple mass-balance modeling indicates that the isotopic composition of the sorbed Fe(II) pool is ∼+1.5‰ to +2.5‰ heavier than Fe in the goethite [∼2.7‰-3.7‰ heavier than aqueous Fe(II)]. Mass balance is also consistent with a pool of heavy Fe that is not released to solution during acid extraction.

Original languageEnglish (US)
Pages (from-to)205-208
Number of pages4
JournalGeology
Volume32
Issue number3
DOIs
StatePublished - Mar 1 2004

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goethite
fractionation
isotope
adsorption
iron
mass balance
electron
experiment
acid
isotopic composition
kinetics
modeling

All Science Journal Classification (ASJC) codes

  • Geology

Cite this

Icopini, G. A. ; Anbar, A. D. ; Ruebush, S. S. ; Tien, Ming ; Brantley, Susan Louise. / Iron isotope fractionation during microbial reduction of iron : The importance of adsorption. In: Geology. 2004 ; Vol. 32, No. 3. pp. 205-208.
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Iron isotope fractionation during microbial reduction of iron : The importance of adsorption. / Icopini, G. A.; Anbar, A. D.; Ruebush, S. S.; Tien, Ming; Brantley, Susan Louise.

In: Geology, Vol. 32, No. 3, 01.03.2004, p. 205-208.

Research output: Contribution to journalArticle

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